AType

Atype is a term used in several disciplines to denote a category labeled with the letter A. The meaning varies by field, and there is no single, universal definition. In reference works, Atype commonly appears in discussions of blood groups, personality typology, and speculative digital typography projects.

In biology, Atype most often refers to the A blood group. People with Atype have A antigens on red blood cells and anti-B antibodies in plasma. Subtypes such as A1 and A2 describe variations in antigen density. Blood compatibility follows ABO matching rules, with A-type recipients able to receive A or O type blood in transfusions.

In psychology, Atype is sometimes used informally to describe Type A personality traits. The paradigm characterizes individuals as competitive, time-conscious, and highly driven. The concept originated from Friedman and Rosenman in the 1950s and has been discussed in relation to stress and cardiovascular risk, though subsequent research has produced mixed findings on causality and strength of association.

In digital typography and motion design, Atype has appeared as the name of a proposed open standard for encoding typography and animation. In speculative or experimental contexts, an Atype format would store vector glyphs, kerning data, and timing information for animated text. No widely adopted specification by this name currently governs mainstream fonts or web typography.